39,616 research outputs found
Investigating Stops in Alaska: Can Coleman Survive a Multifactored Balance
Globalization and centralization have resulted in prolonged transportation time between producer and consumer, and thus put more demand on the perseveration of a product for longer duration and protect it from oxidation. The presence of oxygen in packages severely foreshortens the storage life as it yield losses of nutrients and allow microbial growth, which can cause changes in smell, taste as well as discoloration. Earlier food and beverage containers were made in inorganic materials e.g. metal and glass, however lately more and more focus have been on synthetic organic materials as these show several advantages, e.g. weight. However, still today most of the commercial packaging materials, organic or inorganic, are not considered to be environmental friendly. Thus, efforts have to be made today in order to invent alternative materials that can make the society of tomorrow more sustainable. Cellulose is the most abundant biopolymer in the world, hence making it desirable to use in āgreenā packaging applications. Furthermore, cellulose has proven being able to form films with great gas barrier potential under specific conditions. However, cellulose based materials are sensitive to moisture with severely increased oxygen transmission with increased relative humidity as a result; hence it is desired to make cellulose less hygroscopic by chemical modification. First, nanofibrillated cellulose (NFC) with 720 mmol carboxylic groups/g fiber was produced by oxidation of dissolving pulp before homogenization. Thereafter a polymer was synthesized utilizing Initiator A as an initiator at T1 and T2. The polymer synthesized at T1 yielded a polymer with a viscosity average molecular weight of 5770 g/mol.Ā The polymer was then grafted on the oxidized NFC through a coupling reaction performed in Buffer C using Coupling agent A. The grafting procedure was performed in Buffer C at ambient conditions giving rise to a material composed of 33 wt% synthetic polymer and 67 wt% NFC. The coupling was conducted several times in order to investigate how the final product can be affected by varying reactant feed and dispersion method. Finally, films of NFC and NFC-g-Polymer were manufactured by vacuum filtration from a 0.05 wt% Solvent A dispersion and were evaluated with field emission scanning electron microscopy
Socio-spatial analysis of four university campuses: the implications of spatial configuration on creation and transmission of knowledge
An exploratory study of space use, interaction and students? and academics? subjectiveperceptions of interaction and vitality in the four campus sites of the PontificiaUniversidad CatĆ³lica de Chile (PUC), in Santiago de Chile is presented. The fourcampuses, which differ substantially in their architecture, size and the programmaticnature of the disciplines they house, were modelled as spatial configurations usingspace syntax methods. Observations of patterns of space use and movement werecarried out and a questionnaire survey of staff and students was used to elicit perceptualand reported communication network strengths for both academic staff andstudents. One might expect that, given the twin roles of a university institution in thegeneration of new knowledge and induction of alumni into a ?professional? socialsolidarity, the roles of global and local integration would tend to compete. Globalsegregation in combination with local integration can construct the conditions forstudents to appropriate the open space and generate a powerful local identity at thelevel of the academic unit. However, global integration appears to play an importantrole in making those local solidarities accessible to one another and therefore in thegeneration of new knowledge and solidarities. The data at hand, though exploratoryin nature, suggest that the dynamic is more complex: local identity of the disciplineappears to be a necessary component in the construction of interdisciplinary ?weak?networks at the scale of the institution as a whole
On the Approximation of the Quantum Gates using Lattices
A central question in Quantum Computing is how matrices in can be
approximated by products over a small set of "generators". A topology will be
defined on so as to introduce the notion of a covering exponent
\cite{letter}, which compares the length of products required to covering
with balls against the Haar measure of
balls. An efficient universal set over will be constructed using the
Pauli matrices, using the metric of the covering exponent. Then, the
relationship between and will be manipulated to correlate angles
between points on and give a conjecture on the maximum of angles between
points on a lattice. It will be shown how this conjecture can be used to
compute the covering exponent, and how it can be generalized to universal sets
in .Comment: This is an updated version of arxiv.org:1506.0578
An Evaluation of the effects of DC\u27s voucher program on public school achievement and racial integration after one year
This study evaluates the initial effect Washington D.C.\u27s Opportunity Scholarship Program (OPS) on the academic performance of public schools and its effects on the opportunities District students have to attend integrated schools. OPS is a federally sponsored school voucher program that provides vouchers worth up to $7,500 for an estimated 1,800 to 2,000 students in the District of Columbia. Students can use the scholarships to pay tuition at participating private schools in the District. The pilot program is designed to last for 5 years
Satellite altimeters after Skylab and GEOS-C - should they utilize a single transmitter or an array of pulsed amplifiers?
An attempt was made to determine if future satellite altimeters, operating at K-band, should use a single transmitter or an array of pulsed amplifiers. The two systems were compared as a function of reliability, power, service life, system requirements, and weight. Preliminary results indicate the modular system to be superior in service life and reliability although it requires more power and is substantially heavier than the single system. No concrete conclusions were reached as to which system should be used
Laser-assisted electron-argon scattering at small angles
Electron-argon scattering in the presence of a linearly polarized, low
frequency laser field is studied theoretically. The scattering geometries of
interest are small angles where momentum transfer is nearly perpendicular to
the field, which is where the Kroll-Watson approximation has the potential to
break down. The Floquet R matrix method solves the velocity gauge Schr\"odinger
equation, using a larger reaction volume than previous treatments in order to
carefully assess the importance of the long range polarization potential to the
cross section. A comparison of the cross sections calculated with the target
potential fully included inside 20 and 100 a.u. shows no appreciable
differences, which demonstrates that the long range interaction can not account
for the high cross sections measured in experiments.Comment: 2 figure
NASA/Pratt and Whitney experimental clean combustor program: Engine test results
A two-stage vorbix (vortex burning and mixing) combustor and associated fuel system components were successfully tested in an experimental JT9D engine at steady-state and transient operating conditions, using ASTM Jet-A fuel. Full-scale JT9D experimental engine tests were conducted in a phase three aircraft experimental clean combustor program. The low-pollution combustor, fuel system, and fuel control concepts were derived from phase one and phase two programs in which several combustor concepts were evaluated, refined, and optimized in a component test rig. Significant pollution reductions were achieved with the combustor which meets the performance, operating, and installation requirements of the engine
A tidally interacting disk in the young triple system WL 20?
We present high-resolution Ī» = 2.7 mm imaging of the close triple pre-main-sequence system WL 20. Compact dust emission with integrated flux density of 12.9 Ā± 1.3 mJy is associated with two components of the triple system, WL 20W and WL 20S. No emission above a 3 Ļ level of 3.9 mJy is detected toward the third component, WL 20E, which lies 3."17 (400 AU) due east in projection from its neighbors. A possibly warped structure of ~0.1 M_ā and ā¤3."2 extent encompasses WL 20W and WL 20S, which have a projected separation of 2."25 (~280 AU) along a north-south axis. This structure is most likely a tidally disrupted disk surrounding WL 20S. New near-infrared spectra of the individual components show a remarkable similarity between the two T Tauri stars of the system: WL 20E has a K7 spectral type (T_eff = 4040 K) with r_K = 0.2, and WL 20W has an M0 spectral type (T_eff = 3800 K) with r_K = 0.2. The spectrum of WL 20S is consistent with that of a source intrinsically similar to WL 20W, with r_K < 0.9, but seen through an A_V = 25 in addition to the A_V = 16.3 to the system as a whole. Taken together, these millimeter and infrared data help explain the peculiar nature of the infrared companion, WL 20S, as resulting from a large enhancement in its dusty, circumstellar environment in relation to its companions
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